WPR24LA278

The pilot’s inadvertent use of the landing gear control handle instead of the flaps selector switch during the landing rollout, which resulted in the collapse of the nose landing gear.

The pilot reported that during the landing roll, about the time that he was applying the brakes, the nose landing gear collapsed. Having no training on what to do in this scenario, he cycled the landing gear by raising then lowering the landing gear control handle. Postflight inspection revealed substantial to the undercarriage near the nose landing gear bay. Stored onboard central maintenance computer (CMC) data showed that before touchdown the airplane was properly configured for landing with the flaps at 100%; the nose and both main landing gear were down and locked. After touchdown and during the landing roll, while both weight-on-wheels switches were temporarily unloaded, the landing gear handle was raised and then lowered, which unlocked the nose gear and allowed it to collapse. Additionally, both main landing gear became unlocked, but re-locked before they could collapse. After the nose gear collapse, the gear handle indicated an unexplained 4-second anomaly by indicating neither up nor down, then indicating down. Postaccident examination and a landing gear swing test revealed no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. A missing nose landing gear locking spring from the nose gear assembly was not causal to the accident. The flaps selector switch was located below the landing gear control handle. Further review of CMC data showed that the operators of the airplane often raise the flaps within seconds after touchdown, which was about the time that the nose landing gear collapsed. Although the pilot was familiar with the airplane and had accrued about 102 flight hours within the past 90 days, it is likely that the pilot inadvertently raised the landing gear control handle during the landing roll instead of selecting the flap selector switch to 0%.

On August 9, 2024, about 1750 Pacific daylight time, a Cirrus Design Corp. SF50, N727VB, was substantially damaged when it was involved in an accident near Watsonville, California. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 business flight. According to the pilot, he and a passenger departed the Ogden-Hinkley Airport (OGD) Ogden, Utah, destined for the Watsonville Municipal Airport (WVI) Watsonville, California; he stated that the enroute portion of the flight was uneventful. Upon arrival at WVI, the pilot prepared for landing by lowering the landing gear, confirming that there were three green landing gear indications in the multi-function display (MFD), and confirmed that flaps were set to 100%. The airplane touched down about 80 to 85 knots and the landing was normal. The airplane did not bounce or get light on the wheels after it touched down, and there was no period where only one main landing gear was on the runway. About the time that he began to apply the brakes, the nose landing gear collapsed. Having no training on the event that was occurring, the pilot raised then lowered the landing gear handle with no effect on the already collapsed nose gear. The pilot maintained directional control until the airplane came to a stop. Postflight inspection revealed substantial damage to the undercarriage of the composite fuselage near the nose gear bay, as shown in figure 1. Figure 1. View of the substantial damage to the undercarriage. (Photo courtesy of FAA) The airplane was equipped with a CMC that recorded, in part, landing gear data, flaps position, wheel speed, and weight-on-wheels (WOW) data, all in one-second intervals. A review of ADS-B and downloaded CMC data from the airplane revealed that, at 1250:28 while the airplane was about 1,250 ft from the approach threshold of the runway, the flaps were at 100%, the landing gear handle indicated down, and the nose gear and left and right main landing gear were down and locked. Fourteen seconds later, the airplane touched down, as indicated by the left and right wheel speed increasing from 0 to about 1501 rpm and 1488 rpm respectively. One second later, the WOW data indicated a load on the left and right main landing gear. Two seconds later, the WOW data indicated no load on either landing gear, the gear handle indicated in the down position, and the landing gear indicated down and locked. At 1250:47, the gear handle indicated in the up position and the WOW switches indicated no load; the left and right main landing gear indicated down but not locked, and the nose gear indicated down and locked. At the same time, the hydraulic pack was enabled, and the landing gear was directed up. One second later, the nose gear also indicated down but not locked. At the same time, the left WOW switch indicated no load, and the right WOW switch indicated a load. The hydraulic pack remained enabled, and the landing gear continued to be directed up. At 1250:49, the gear handle indicated down; the nose gear indicated not down and not locked. The left and right main landing gear indicated down but not locked. The hydraulic pump was enabled, and the gear was not directed up. The airplane indicated a 12.5° nose-down attitude. From 1250:50 until 1250:54, the gear handle indicated neither up nor down. One second later the gear handle indicated down. A review of the CMC data for the last twelve flights revealed that flap retraction from 100% to 0% occurred anywhere from 2 seconds after touchdown to 70 seconds after touchdown, with 8 out of 10 times being within 2 to 5 seconds after touchdown. The accident flight recorded no flap retraction. A postaccident examination of the airframe and landing gear revealed one of the two nose landing gear (NLG) locking springs was absent from the nose gear assembly, as illustrated in figure 2. Figure 2. Illustration of the nose landing gear showing the two NLG locking springs. (Image courtesy of Cirrus Design Corporation) According to the manufacturer, the NLG locking springs are installed to assist the gear into the locked position during an alternate/freefall extension, and the second spring is strictly for redundancy. According to the SF50 Pilot’s Information Manual, the landing gear control handle is located at the center instrument panel, in between the primary flight display and the multi-function display. The three-position flap selector switch is located at the center consol forward and to the right of the thrust lever. The flaps are UP, 50% and 100%. (See figure 3.) Figure 3. Illustration of the SF50 cockpit showing the landing gear control handle location and the flaps selector switch location. (Illustration courtesy of Cirrus Design Corporation) The airplane was stabilized using floor jacks and a tail stand. A functional test of the landing gear revealed no preaccident mechanical malfunctions or failures with the landing gear that would have precluded normal operation. A review of maintenance records revealed the airplane underwent an annual inspection on April 10, 2024, which included a check of the landing gear. No anomalies were noted. The pilot reported 4,300 total flight hours experience, which included 443.4 hours flying experience in the SF50. He had accrued 102.5 hours in the SF50 within the last 90 days, 50.9 hours within the last 30 days, and 4.0 hours in the last 24 hours.